Patent Literature 1 proposes a method for fixing magnets within a magnet accommodation hole which is formed in a substantially cylindrical rotor core along an axial direction thereof. This fixing method is a method comprising, as FIGS. 4A, 4B show, the steps of forming a rotor core 60 by stacking and fixed therein a plurality of electromagnetic steel plates (core pieces) 69, accommodating magnet pieces 62 in a magnet accommodation hole 61 in the rotor core 60, and filling a resin 63 into the magnet accommodation hole 61 from a resin pot 65 formed in an upper mold 64 for integration of the rotor core 60 with the resin. Here, in the figures, reference numeral 67 denotes a plunger for pushing the resin 63 out, and reference numeral 68 denotes a lower mold.